This invention relates a method of forming a black matrix or color filter for cathode ray tubes and more particularly, to a method of readily forming a fluorescent screen on a front panel of a cathode ray tube with high accuracy.
For the formation of a black matrix or fluorescent screen on a front panel of a cathode ray tube in related art, a so-called wet photolithographic method has been employed including the steps of slurry coating, exposure to light and wet development. However, this method is disadvantageous in that it includes a number of the steps and an apparatus for carrying out the method is complicated, with poor productivity. Instead, methods using printing techniques such as screen printing have been proposed as a method of forming a black matrix with high productivity (set out, for example, in Japanese Patent Publication No. Sho 55-46674 and Japanese Patent Laid-open No. Hei 6-49398).
Recently, it has been reported that the contrast of a color cathode ray tube is effectively improved by selective suppression of external light reflection by providing pigment layers, i.e. color filters, corresponding to red, blue and green colors in front of red, blue and green-colored fluorescent films. This is described, for example, in Japanese Patent Laid-open No. Hei 5-275008 and Shin-Gaku Technical Report EID 93-102 (1994-01) at page 17. The color filters are formed by a so-called wet photolithographic method including slurry coating, light exposure and wet development, like the known method of forming a fluorescent film on a face plate or front panel of a cathode ray tube.
The above-mentioned screen printing method is high in productivity and is very advantageous from the standpoint of manufacturing facilities, but has the problem, in comparison with the wet photolithographic method, in that the registration accuracy is poorer and especially, it is not suitable for forming a large-sized cathode ray tube.
On the other hand, as stated before, the wet photolithographic method has the drawbacks that it includes a very great number of steps including the step of forming a fluorescent film and that an apparatus becomes complicated and intricate, resulting in poor productivity.